In the inflammatory microenvironment,there are numerous exosomes secreted by immune cells(Macrophages,neutrophils,dendritic cells),mesenchymal stem cells(MSCs)and platelets as intercellular communicators,which partici...In the inflammatory microenvironment,there are numerous exosomes secreted by immune cells(Macrophages,neutrophils,dendritic cells),mesenchymal stem cells(MSCs)and platelets as intercellular communicators,which participate in the regulation of inflammation by modulating gene expression and releasing anti-inflammatory factors.Due to their good biocompatibility,accurate targeting,low toxicity and immunogenicity,these exosomes are able to selectively deliver therapeutic drugs to the site of inflammation through interactions between their surface-antibody or modified ligand with cell surface receptors.Therefore,the role of exosome-based biomimetic delivery strategies in inflammatory diseases has attracted increasing attention.Here we review current knowledge and techniques for exosome identification,isolation,modification and drug loading.More importantly,we highlight progress in using exosomes to treat chronic inflammatory diseases such as rheumatoid arthritis(RA),osteoarthritis(OA),atherosclerosis(AS),and inflammatory bowel disease(IBD).Finally,we also discuss their potential and challenges as anti-inflammatory drug carriers.展开更多
Text similarity has a relatively wide range of applications in many fields, such as intelligent information retrieval, question answering system, text rechecking, machine translation, and so on. The text similarity co...Text similarity has a relatively wide range of applications in many fields, such as intelligent information retrieval, question answering system, text rechecking, machine translation, and so on. The text similarity computing based on the meaning has been used more widely in the similarity computing of the words and phrase. Using the knowledge structure of the and its method of knowledge description, taking into account the other factor and weight that influenced similarity, making full use of depth and density of the Concept-Sememe tree, an improved method of Chinese word similarity calculation based on semantic distance was provided in this paper. Finally the effectiveness of this method was verified by the simulation results.展开更多
The relationship between RSSI (Received Signal Strength Indication) values and distance is the foundation and the key of ranging and positioning technologies in wireless sensor networks. Log-normal shadowing model (LN...The relationship between RSSI (Received Signal Strength Indication) values and distance is the foundation and the key of ranging and positioning technologies in wireless sensor networks. Log-normal shadowing model (LNSM), as a more general signal propagation model, can better describe the relationship between the RSSI value and distance, but the parameter of variance in LNSM is depended on experiences without self-adaptability. In this paper, it is found that the variance of RSSI value changes along with distance regu- larly by analyzing a large number of experimental data. Based on the result of analysis, we proposed the relationship function of the variance of RSSI and distance, and established the log-normal shadowing model with dynamic variance (LNSM-DV). At the same time, the method of least squares(LS) was selected to es- timate the coefficients in that model, thus LNSM-DV might be adjusted dynamically according to the change of environment and be self-adaptable. The experimental results show that LNSM-DV can further reduce er- ror, and have strong self-adaptability to various environments compared with the LNSM.展开更多
Necrosis of nipple-areola complex is one of the major complications of breast reduction in gigatomastia.Wie present a case study of a 32-year-old patient with severe gigantomastia,who required an immediate nipple reco...Necrosis of nipple-areola complex is one of the major complications of breast reduction in gigatomastia.Wie present a case study of a 32-year-old patient with severe gigantomastia,who required an immediate nipple reconstruction during breast reduction.The final reconstruction was satisfactory.No complications were observed within three months postoperatively.展开更多
We present an imaging approach via sparsity constraint and sparse speckle illumination which can dramatically en- hance the optical system's imaging resolution. When the object is illuminated by some sparse speckles ...We present an imaging approach via sparsity constraint and sparse speckle illumination which can dramatically en- hance the optical system's imaging resolution. When the object is illuminated by some sparse speckles and the sparse reconstruction algorithm is utilized to restore the blur image, numerical simulated results demonstrate that the image, whose resolution exceeds the Rayleigh limit, can be stably reconstructed even if the detection signal-to-noise ratio (SNR) is less than 10 dB. Factors affecting the quality of the reconstructed image, such as the coded pattern's sparsity and the detection SNR, are also studied,展开更多
Existing pressure drilling technologies are based on different principles and display distinct characteristics in terms of control pressure and degree of formation adaptability.In the present study,the constant-bottom...Existing pressure drilling technologies are based on different principles and display distinct characteristics in terms of control pressure and degree of formation adaptability.In the present study,the constant-bottomhole-pressure(CBHP)and controlled-mud-level(CML)dual gradient drilling methods are considered.Models for the equivalent circulating density(ECD)are introduced for both drilling methods,taking into account the control pressure parameters(wellhead back pressure,displacement,mud level,etc.)and the relationship between the equivalent circulating density curve in the wellbore and two different types of pressure profiles in deep-water areas.The findings suggest that the main pressure control parameter for CBHP drilling is the wellhead back pressure,while for CML dual gradient drilling,it is the mud level.Two examples are considered(wells S1 and B2).For S1,CML dual gradient drilling only needs to adjust the ECD curve once to drill down to the target layer without risk.By comparison,CBHP drilling requires multiple adjustments to reach the target well depth avoiding a kick risk.In well B2,the CBHP method can drill down to the desired zone or even deeper after a single adjustment of the ECD curve.In contrast,CML dual-gradient drilling requires multiple adjustments to reach the target well depth(otherwise there is a risk of lost circulation).Therefore,CML dual-gradient drilling should be considered as a better choice for well S1,while CBHP drilling is more suitable for well B2.展开更多
[Objectives]To establish a quality analysis method for Guangxi Zhuang medicine Lysimachia foenum-graecum Hance.[Methods]The moisture,total ash and alcohol-soluble extracts of L.foenum-graecum medicinal materials were ...[Objectives]To establish a quality analysis method for Guangxi Zhuang medicine Lysimachia foenum-graecum Hance.[Methods]The moisture,total ash and alcohol-soluble extracts of L.foenum-graecum medicinal materials were determined in accordance with the inspection method of the Chinese Pharmacopoeia(2015).[Results]The 10 batches of L.foenum-graecum medicinal materials from different origins and different collection times in Guangxi all had the same plant morphology and medicinal properties.The moisture content was 5.69%-10.51%,the total ash content was 5.50%-8.61%,the acid-insoluble ash content was 0.42%-0.78%,and the extract was 15.28%-20.75%.[Conclusions]This study is expected to provide a scientific basis for the development and utilization of L.foenum-graecum medicinal materials and the establishment of its quality standards.展开更多
Transition metal-catalyzed carbometallation of unsaturated hydrocarbons constitutes one of the most efficient synthetic methodologies for the construction of C—C bond.Recently,the incorporation of organometallic reag...Transition metal-catalyzed carbometallation of unsaturated hydrocarbons constitutes one of the most efficient synthetic methodologies for the construction of C—C bond.Recently,the incorporation of organometallic reagent with the CO gas as a nucleophilic acyl synthon could enable the acylmetallation reaction,which greatly increases the horizon of carbometallation chemistry.Herein,we report a nickel-catalyzed regiodivergent acylzincation of o-cyano cinnamate ester and o-cyano styrene,in which the cyano moiety intramolecularly captures zinc intermediates to trigger the tandem cyclization process.This protocol features mild conditions,broad substrate scope and excellent functional group tolerance,thus affording a diverse array of highly functionalized carbocyclic compounds.展开更多
In this study,a novel lubricant additive nitrogen-doped carbon quantum dot(N-CQD)nanoparticle was prepared by the solvothermal method.The synthesized spherical N-CQD nanoparticles in the diameter of about 10 nm had a ...In this study,a novel lubricant additive nitrogen-doped carbon quantum dot(N-CQD)nanoparticle was prepared by the solvothermal method.The synthesized spherical N-CQD nanoparticles in the diameter of about 10 nm had a graphene oxide(GO)-like structure with various oxygen(O)-and nitrogen(N)-containing functional groups.Then N-CQDs were added to MoS_(2)nanofluid,and the tribological properties for steel/steel friction pairs were evaluated using a pin-on-disk tribometer.Non-equilibrium molecular dynamics(NEMD)simulations for the friction system with MoS_(2)or MoS_(2)+N-CQD nanoparticles were also conducted.The results showed that friction processes with MoS_(2)+N-CQD nanofluids were under the mixed lubrication regime.And MoS_(2)nanofluid containing 0.4 wt%N-CQDs could achieve 30.4%and 31.0%reduction in the friction coefficient and wear rate,respectively,compared to those without N-CQDs.By analyzing the worn surface topography and chemical compositions,the excellent lubrication performance resulted from the formation of tribochemistry-induced tribofilm.The average thickness of tribofilm was about 13.9 nm,and it was composed of amorphous substances,ultrafine crystalline nanoparticles,and self-lubricating FeSO_(4)/Fe2(SO_(4))_(3).NEMD simulation results indicated the interaction between S atoms in MoS_(2)as well as these O-and N-containing functional groups in N-CQDs with steel surfaces enhanced the stability and strength of tribofilm.Thereby the metal surface was further protected from friction and wear.展开更多
Small nucleolar RNAs(snoRNAs)play critical roles in various biological processes.The aberrant expression or depletion of snoRNAs is related to various diseases.In previous research,most of the snoRNAs were categorized...Small nucleolar RNAs(snoRNAs)play critical roles in various biological processes.The aberrant expression or depletion of snoRNAs is related to various diseases.In previous research,most of the snoRNAs were categorized as C/D box snoRNAs and H/ACA box snoRNAs,whose typical functions were thought of as regulation of 2′-O-ribose methylation and pseudouridylation of ribosome RNAs,respectively.However,in the past two decades,studies have revealed an increasing number of snoRNAs without specific targets or determined cell functions.These findings indicated that some potential roles of snoRNAs are still unknown.Numerous studies have indicated the correlation of snoRNAs with human diseases.SnoRNAs play various roles in abundant biological processes,and they have great potential in controlling human diseases.This new and rising field could benefit from investigations of the disease pathogenesis,biomarker identification,and the determination of novel therapeutic targets.This review summarized the reports on snoRNAs and the regulation of different diseases in recent years.展开更多
Shale hydration and swelling is the main obstacle to the development of shale gas utilizing water-based drilling fluids(WBDFs).In this work,the inhibition mechanism of alkylammonium inhibitor and alkylamine inhibitor ...Shale hydration and swelling is the main obstacle to the development of shale gas utilizing water-based drilling fluids(WBDFs).In this work,the inhibition mechanism of alkylammonium inhibitor and alkylamine inhibitor adsorbed on sodium bentonite(Na+Bent)are investigated using infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),X-ray diffraction(XRD),zeta potential,particle size distribution tests,and thermogravimetry analysis(TGA).The results suggest that HTB and HMD can be inserted into the interlamination of Na+Bent and minimize the basal spacing compared to hydrated Na+Bent.HTB and HMD are inserted between the Na+Bent layers in a single-layer tiled manner and replace the sodium ions that are firmly fixed between the layers.Eventually,water molecules are removed from the interlayer Na+Bent.The interaction between the quaternary ammonium group and Na+Bent is more significant than between the primary amine group and Na+Bent.The inhibition performance suggests that HTB inhibits Na+Bent hydration and swelling more substantially than other inhibitors,indicating that the inhibition performance of the two quaternary ammonium groups is greater than that of the two primary amine groups.Therefore,HTB can be used as intercalation inhibition in WBDFs and has tremendous application value.展开更多
The effect of background light on the imaging quality of three typical ghost imaging(GI) lidar systems(namely narrow pulsed GI lidar, heterodyne GI lidar, and pulse-compression GI lidar via coherent detection) is inve...The effect of background light on the imaging quality of three typical ghost imaging(GI) lidar systems(namely narrow pulsed GI lidar, heterodyne GI lidar, and pulse-compression GI lidar via coherent detection) is investigated. By computing the signal-to-noise ratio(SNR) of fluctuation-correlation GI, our analytical results, which are backed up by numerical simulations, demonstrate that pulse-compression GI lidar via coherent detection has the strongest capacity against background light, whereas the reconstruction quality of narrow pulsed GI lidar is the most vulnerable to background light. The relationship between the peak SNR of the reconstruction image andσ(namely, the signal power to background power ratio) for the three GI lidar systems is also presented, and theresults accord with the curve of SNR-σ.展开更多
Ghost imaging(GI)facilitates image acquisition under low-light conditions by single-pixel measurements and thus has great potential in applications in various fields ranging from biomedical imaging to remote sensing.H...Ghost imaging(GI)facilitates image acquisition under low-light conditions by single-pixel measurements and thus has great potential in applications in various fields ranging from biomedical imaging to remote sensing.However,GI usually requires a large amount of single-pixel samplings in order to reconstruct a high-resolution image,imposing a practical limit for its applications.Here we propose a far-field super-resolution GI technique that incorporates the physical model for GI image formation into a deep neural network.The resulting hybrid neural network does not need to pre-train on any dataset,and allows the reconstruction of a far-field image with the resolution beyond the diffraction limit.Furthermore,the physical model imposes a constraint to the network output,making it effectively interpretable.We experimentally demonstrate the proposed GI technique by imaging a flying drone,and show that it outperforms some other widespread GI techniques in terms of both spatial resolution and sampling ratio.We believe that this study provides a new framework for GI,and paves a way for its practical applications.展开更多
Single-pixel imaging(SPI) is a typical computational imaging modality that allows two-and three-dimensional image reconstruction from a one-dimensional bucket signal acquired under structured illumination.It is in par...Single-pixel imaging(SPI) is a typical computational imaging modality that allows two-and three-dimensional image reconstruction from a one-dimensional bucket signal acquired under structured illumination.It is in particular of interest for imaging under low light conditions and in spectral regions where good cameras are unavailable.However,the resolution of the reconstructed image in SPI is strongly dependent on the number of measurements in the temporal domain.Data-driven deep learning has been proposed for high-quality image reconstruction from a undersampled bucket signal.But the generalization issue prohibits its practical application.Here we propose a physics-enhanced deep learning approach for SPI.By blending a physics-informed layer and a model-driven fine-tuning process,we show that the proposed approach is generalizable for image reconstruction.We implement the proposed method in an in-house SPI system and an outdoor single-pixel LiDAR system,and demonstrate that it outperforms some other widespread SPI algorithms in terms of both robustness and fidelity.The proposed method establishes a bridge between data-driven and model-driven algorithms,allowing one to impose both data and physics priors for inverse problem solvers in computational imaging,ranging from remote sensing to microscopy.展开更多
The features of the characteristic matrix used in linear intensity correlation reconstruction methods are directly related to the quality of ghost imaging. In order to suppress the noise caused by the off-diagonal ele...The features of the characteristic matrix used in linear intensity correlation reconstruction methods are directly related to the quality of ghost imaging. In order to suppress the noise caused by the off-diagonal elements in the characteristic matrix, we propose a reconstruction method for ghost imaging called scalar-matrix-structured ghost imaging(SMGI). The characteristic matrix is made to approximate a scalar matrix by modifying the measurement matrix. Experimental results show that SMGI improves the peak signal-to-noise ratio of the object reconstruction significantly compared with differential ghost imaging, even in the case of a nonzero two-arm longitudinal difference, which is a promising result for practical applications.展开更多
Space nuclear reactor power(SNRP)using a gas-cooled reactor(GCR)and a closed Brayton cycle(CBC)is the ideal choice for future high-power space missions.To investigate the safety characteristics and develop the control...Space nuclear reactor power(SNRP)using a gas-cooled reactor(GCR)and a closed Brayton cycle(CBC)is the ideal choice for future high-power space missions.To investigate the safety characteristics and develop the control strategies for gas-cooled SNRP,transient models for GCR,energy conversion unit,pipes,heat exchangers,pump and heat pipe radiator are established and a system analysis code is developed in this paper.Then,analyses of several operation conditions are performed using this code.In full-power steady-state operation,the core hot spot of 1293 K occurs near the upper part of the core.If 0.4$reactivity is introduced into the core,the maximum temperature that the fuel can reach is 2059 K,which is 914 K lower than the fuel melting point.The system finally has the ability to achieve a new steady-state with a higher reactor power.When the GCR is shut down in an emergency,the residual heat of the reactor can be removed through the conduction of the core and radiation heat transfer.The results indicate that the designed GCR is inherently safe owing to its negative reactivity feedback and passive decay heat removal.This paper may provide valuable references for safety design and analysis of the gas-cooled SNRP coupled with CBC.展开更多
We propose a color ghost imaging approach where the object is illuminated by three-color non-orthogonal random patterns. The object’s reflection/transmission information is received by only one single-pixel detector,...We propose a color ghost imaging approach where the object is illuminated by three-color non-orthogonal random patterns. The object’s reflection/transmission information is received by only one single-pixel detector, and both the sparsity constraint and non-local self-similarity of the object are utilized in the image reconstruction process. Numerical simulation results demonstrate that the imaging quality can be obviously enhanced by ghost imaging via sparsity constraint and nonlocal self-similarity(GISCNL), compared with the reconstruction methods where only the object’s sparsity is used. Factors affecting the quality of GISCNL, such as the measurement number and the detection signal-to-noise ratio, are also studied.展开更多
基金by the National Natural Science Foundation of China[grant numbers 82170459,2021]Sichuan Science and Technology Program[grant numbers 2022YFH0007,2022]+2 种基金Sichuan Science and Technology Program[grant numbers 23NSFSC1345,2022]the Key Project of Application and Basic Research of Southwest Medical University[grant numbers 2021ZKZD016,2021]the Special Support Project for Young Talents of Southwest Medical University[grant numbers 2020-2022].
文摘In the inflammatory microenvironment,there are numerous exosomes secreted by immune cells(Macrophages,neutrophils,dendritic cells),mesenchymal stem cells(MSCs)and platelets as intercellular communicators,which participate in the regulation of inflammation by modulating gene expression and releasing anti-inflammatory factors.Due to their good biocompatibility,accurate targeting,low toxicity and immunogenicity,these exosomes are able to selectively deliver therapeutic drugs to the site of inflammation through interactions between their surface-antibody or modified ligand with cell surface receptors.Therefore,the role of exosome-based biomimetic delivery strategies in inflammatory diseases has attracted increasing attention.Here we review current knowledge and techniques for exosome identification,isolation,modification and drug loading.More importantly,we highlight progress in using exosomes to treat chronic inflammatory diseases such as rheumatoid arthritis(RA),osteoarthritis(OA),atherosclerosis(AS),and inflammatory bowel disease(IBD).Finally,we also discuss their potential and challenges as anti-inflammatory drug carriers.
文摘Text similarity has a relatively wide range of applications in many fields, such as intelligent information retrieval, question answering system, text rechecking, machine translation, and so on. The text similarity computing based on the meaning has been used more widely in the similarity computing of the words and phrase. Using the knowledge structure of the and its method of knowledge description, taking into account the other factor and weight that influenced similarity, making full use of depth and density of the Concept-Sememe tree, an improved method of Chinese word similarity calculation based on semantic distance was provided in this paper. Finally the effectiveness of this method was verified by the simulation results.
文摘The relationship between RSSI (Received Signal Strength Indication) values and distance is the foundation and the key of ranging and positioning technologies in wireless sensor networks. Log-normal shadowing model (LNSM), as a more general signal propagation model, can better describe the relationship between the RSSI value and distance, but the parameter of variance in LNSM is depended on experiences without self-adaptability. In this paper, it is found that the variance of RSSI value changes along with distance regu- larly by analyzing a large number of experimental data. Based on the result of analysis, we proposed the relationship function of the variance of RSSI and distance, and established the log-normal shadowing model with dynamic variance (LNSM-DV). At the same time, the method of least squares(LS) was selected to es- timate the coefficients in that model, thus LNSM-DV might be adjusted dynamically according to the change of environment and be self-adaptable. The experimental results show that LNSM-DV can further reduce er- ror, and have strong self-adaptability to various environments compared with the LNSM.
文摘Necrosis of nipple-areola complex is one of the major complications of breast reduction in gigatomastia.Wie present a case study of a 32-year-old patient with severe gigantomastia,who required an immediate nipple reconstruction during breast reduction.The final reconstruction was satisfactory.No complications were observed within three months postoperatively.
基金Project supported by the National Natural Science Foundation of China(Grant No.61571427)
文摘We present an imaging approach via sparsity constraint and sparse speckle illumination which can dramatically en- hance the optical system's imaging resolution. When the object is illuminated by some sparse speckles and the sparse reconstruction algorithm is utilized to restore the blur image, numerical simulated results demonstrate that the image, whose resolution exceeds the Rayleigh limit, can be stably reconstructed even if the detection signal-to-noise ratio (SNR) is less than 10 dB. Factors affecting the quality of the reconstructed image, such as the coded pattern's sparsity and the detection SNR, are also studied,
文摘Existing pressure drilling technologies are based on different principles and display distinct characteristics in terms of control pressure and degree of formation adaptability.In the present study,the constant-bottomhole-pressure(CBHP)and controlled-mud-level(CML)dual gradient drilling methods are considered.Models for the equivalent circulating density(ECD)are introduced for both drilling methods,taking into account the control pressure parameters(wellhead back pressure,displacement,mud level,etc.)and the relationship between the equivalent circulating density curve in the wellbore and two different types of pressure profiles in deep-water areas.The findings suggest that the main pressure control parameter for CBHP drilling is the wellhead back pressure,while for CML dual gradient drilling,it is the mud level.Two examples are considered(wells S1 and B2).For S1,CML dual gradient drilling only needs to adjust the ECD curve once to drill down to the target layer without risk.By comparison,CBHP drilling requires multiple adjustments to reach the target well depth avoiding a kick risk.In well B2,the CBHP method can drill down to the desired zone or even deeper after a single adjustment of the ECD curve.In contrast,CML dual-gradient drilling requires multiple adjustments to reach the target well depth(otherwise there is a risk of lost circulation).Therefore,CML dual-gradient drilling should be considered as a better choice for well S1,while CBHP drilling is more suitable for well B2.
基金Key Research and Development Program of Department of Science and Technology of Guangxi Zhuang Autonomous Region(AB19110003)Scientific Research Program of Guangxi International Zhuang Medical Hospital in 2020(GZ202001)+2 种基金Project for Improving Basic Research Ability of Middle Aged and Young Teachers in Colleges and Universities of Guangxi in 2019(2019KY0341)Open Program of Key Laboratory of Zhuang and Yao Medicine(GXZYKF2020A-08)Youth Foundation Project of Guangxi University of Chinese Medicine(2019QN036).
文摘[Objectives]To establish a quality analysis method for Guangxi Zhuang medicine Lysimachia foenum-graecum Hance.[Methods]The moisture,total ash and alcohol-soluble extracts of L.foenum-graecum medicinal materials were determined in accordance with the inspection method of the Chinese Pharmacopoeia(2015).[Results]The 10 batches of L.foenum-graecum medicinal materials from different origins and different collection times in Guangxi all had the same plant morphology and medicinal properties.The moisture content was 5.69%-10.51%,the total ash content was 5.50%-8.61%,the acid-insoluble ash content was 0.42%-0.78%,and the extract was 15.28%-20.75%.[Conclusions]This study is expected to provide a scientific basis for the development and utilization of L.foenum-graecum medicinal materials and the establishment of its quality standards.
基金supported by the National Natural Science Foundation of China(22171079,22371071)the Natural Science Foundation of Shanghai(21ZR1480400)+5 种基金the Shanghai Rising-Star Program(20QA1402300)the Shanghai Sailing Program(23YF1408800)the Shanghai Municipal Science and Technology Major Project(Grant No.2018SHZDZX03)the Program of Introducing Talents of Discipline to Universities(B16017)the China Postdoctoral Science Foundation(2021M701197,2023T160215)the Fundamental Research Funds for the Central Universities.
文摘Transition metal-catalyzed carbometallation of unsaturated hydrocarbons constitutes one of the most efficient synthetic methodologies for the construction of C—C bond.Recently,the incorporation of organometallic reagent with the CO gas as a nucleophilic acyl synthon could enable the acylmetallation reaction,which greatly increases the horizon of carbometallation chemistry.Herein,we report a nickel-catalyzed regiodivergent acylzincation of o-cyano cinnamate ester and o-cyano styrene,in which the cyano moiety intramolecularly captures zinc intermediates to trigger the tandem cyclization process.This protocol features mild conditions,broad substrate scope and excellent functional group tolerance,thus affording a diverse array of highly functionalized carbocyclic compounds.
基金This work was supported by the National Natural Science Foundation of China(No.51874036)Beijing Municipal Natural Science Foundation(No.2182041).
文摘In this study,a novel lubricant additive nitrogen-doped carbon quantum dot(N-CQD)nanoparticle was prepared by the solvothermal method.The synthesized spherical N-CQD nanoparticles in the diameter of about 10 nm had a graphene oxide(GO)-like structure with various oxygen(O)-and nitrogen(N)-containing functional groups.Then N-CQDs were added to MoS_(2)nanofluid,and the tribological properties for steel/steel friction pairs were evaluated using a pin-on-disk tribometer.Non-equilibrium molecular dynamics(NEMD)simulations for the friction system with MoS_(2)or MoS_(2)+N-CQD nanoparticles were also conducted.The results showed that friction processes with MoS_(2)+N-CQD nanofluids were under the mixed lubrication regime.And MoS_(2)nanofluid containing 0.4 wt%N-CQDs could achieve 30.4%and 31.0%reduction in the friction coefficient and wear rate,respectively,compared to those without N-CQDs.By analyzing the worn surface topography and chemical compositions,the excellent lubrication performance resulted from the formation of tribochemistry-induced tribofilm.The average thickness of tribofilm was about 13.9 nm,and it was composed of amorphous substances,ultrafine crystalline nanoparticles,and self-lubricating FeSO_(4)/Fe2(SO_(4))_(3).NEMD simulation results indicated the interaction between S atoms in MoS_(2)as well as these O-and N-containing functional groups in N-CQDs with steel surfaces enhanced the stability and strength of tribofilm.Thereby the metal surface was further protected from friction and wear.
基金supported by the National Natural Science Foundation of China(No.82172473,82072462,81802191)the Natural Science Foundation of Shandong Province,China(No.ZR2019PH068)+1 种基金Public Welfare Basic Research Program of Zhejiang Province,China(No.LY20H060002)2018 Xinhua-uOttawa joint clinical research,China(No.18JX008).
文摘Small nucleolar RNAs(snoRNAs)play critical roles in various biological processes.The aberrant expression or depletion of snoRNAs is related to various diseases.In previous research,most of the snoRNAs were categorized as C/D box snoRNAs and H/ACA box snoRNAs,whose typical functions were thought of as regulation of 2′-O-ribose methylation and pseudouridylation of ribosome RNAs,respectively.However,in the past two decades,studies have revealed an increasing number of snoRNAs without specific targets or determined cell functions.These findings indicated that some potential roles of snoRNAs are still unknown.Numerous studies have indicated the correlation of snoRNAs with human diseases.SnoRNAs play various roles in abundant biological processes,and they have great potential in controlling human diseases.This new and rising field could benefit from investigations of the disease pathogenesis,biomarker identification,and the determination of novel therapeutic targets.This review summarized the reports on snoRNAs and the regulation of different diseases in recent years.
基金supported by the Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(NO.2020CX040102,2020CX040201)National key R&D projects(No.2019YFA0708303)+3 种基金Sichuan Science and Technology Program(No.2020JDJQ0057)Sichuan Youth Science and technology innovation research team project(No.2020JDTD0018)Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(No.2020CX040102,2020CX040201)the Opening Project of Oil&Gas Field Applied Chemistry Key Laboratory of Sichuan Province(YQKF202101).
文摘Shale hydration and swelling is the main obstacle to the development of shale gas utilizing water-based drilling fluids(WBDFs).In this work,the inhibition mechanism of alkylammonium inhibitor and alkylamine inhibitor adsorbed on sodium bentonite(Na+Bent)are investigated using infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),X-ray diffraction(XRD),zeta potential,particle size distribution tests,and thermogravimetry analysis(TGA).The results suggest that HTB and HMD can be inserted into the interlamination of Na+Bent and minimize the basal spacing compared to hydrated Na+Bent.HTB and HMD are inserted between the Na+Bent layers in a single-layer tiled manner and replace the sodium ions that are firmly fixed between the layers.Eventually,water molecules are removed from the interlayer Na+Bent.The interaction between the quaternary ammonium group and Na+Bent is more significant than between the primary amine group and Na+Bent.The inhibition performance suggests that HTB inhibits Na+Bent hydration and swelling more substantially than other inhibitors,indicating that the inhibition performance of the two quaternary ammonium groups is greater than that of the two primary amine groups.Therefore,HTB can be used as intercalation inhibition in WBDFs and has tremendous application value.
基金National Natural Science Foundation of China(NSFC)(61571427)Ministry of Science and Technology of the People’s Republic of China(MOST)(2013AA122901)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2013162)
文摘The effect of background light on the imaging quality of three typical ghost imaging(GI) lidar systems(namely narrow pulsed GI lidar, heterodyne GI lidar, and pulse-compression GI lidar via coherent detection) is investigated. By computing the signal-to-noise ratio(SNR) of fluctuation-correlation GI, our analytical results, which are backed up by numerical simulations, demonstrate that pulse-compression GI lidar via coherent detection has the strongest capacity against background light, whereas the reconstruction quality of narrow pulsed GI lidar is the most vulnerable to background light. The relationship between the peak SNR of the reconstruction image andσ(namely, the signal power to background power ratio) for the three GI lidar systems is also presented, and theresults accord with the curve of SNR-σ.
基金the National Natural Science Foundation of China(61991452,62061136005)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(QYZDB-SSW-JSC002)the Sino-German Center(GZ1391).
文摘Ghost imaging(GI)facilitates image acquisition under low-light conditions by single-pixel measurements and thus has great potential in applications in various fields ranging from biomedical imaging to remote sensing.However,GI usually requires a large amount of single-pixel samplings in order to reconstruct a high-resolution image,imposing a practical limit for its applications.Here we propose a far-field super-resolution GI technique that incorporates the physical model for GI image formation into a deep neural network.The resulting hybrid neural network does not need to pre-train on any dataset,and allows the reconstruction of a far-field image with the resolution beyond the diffraction limit.Furthermore,the physical model imposes a constraint to the network output,making it effectively interpretable.We experimentally demonstrate the proposed GI technique by imaging a flying drone,and show that it outperforms some other widespread GI techniques in terms of both spatial resolution and sampling ratio.We believe that this study provides a new framework for GI,and paves a way for its practical applications.
基金National Natural Science Foundation of China(61991452, 62061136005)Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(QYZDB-SSW-JSC002)Chinesisch-Deutsche Zentrum für Wissenschaftsf?rderung (GZ1391)。
文摘Single-pixel imaging(SPI) is a typical computational imaging modality that allows two-and three-dimensional image reconstruction from a one-dimensional bucket signal acquired under structured illumination.It is in particular of interest for imaging under low light conditions and in spectral regions where good cameras are unavailable.However,the resolution of the reconstructed image in SPI is strongly dependent on the number of measurements in the temporal domain.Data-driven deep learning has been proposed for high-quality image reconstruction from a undersampled bucket signal.But the generalization issue prohibits its practical application.Here we propose a physics-enhanced deep learning approach for SPI.By blending a physics-informed layer and a model-driven fine-tuning process,we show that the proposed approach is generalizable for image reconstruction.We implement the proposed method in an in-house SPI system and an outdoor single-pixel LiDAR system,and demonstrate that it outperforms some other widespread SPI algorithms in terms of both robustness and fidelity.The proposed method establishes a bridge between data-driven and model-driven algorithms,allowing one to impose both data and physics priors for inverse problem solvers in computational imaging,ranging from remote sensing to microscopy.
基金Natural Science Foundation of Science and Technology Development Program of Jilin Province,China(20160101284JC)Hi-Tech Research and Development Program of China(2013AA122901)+1 种基金National Natural Science Foundation of China(NSFC)(61571427)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2013162)
文摘The features of the characteristic matrix used in linear intensity correlation reconstruction methods are directly related to the quality of ghost imaging. In order to suppress the noise caused by the off-diagonal elements in the characteristic matrix, we propose a reconstruction method for ghost imaging called scalar-matrix-structured ghost imaging(SMGI). The characteristic matrix is made to approximate a scalar matrix by modifying the measurement matrix. Experimental results show that SMGI improves the peak signal-to-noise ratio of the object reconstruction significantly compared with differential ghost imaging, even in the case of a nonzero two-arm longitudinal difference, which is a promising result for practical applications.
基金the National Natural Science Foundation of China(Grant No.U1967203)the National Key R&D Program of China(Grant No.2019YFB1901100)and China Postdoctoral Science Foundation(Grant No.2019M3737).
文摘Space nuclear reactor power(SNRP)using a gas-cooled reactor(GCR)and a closed Brayton cycle(CBC)is the ideal choice for future high-power space missions.To investigate the safety characteristics and develop the control strategies for gas-cooled SNRP,transient models for GCR,energy conversion unit,pipes,heat exchangers,pump and heat pipe radiator are established and a system analysis code is developed in this paper.Then,analyses of several operation conditions are performed using this code.In full-power steady-state operation,the core hot spot of 1293 K occurs near the upper part of the core.If 0.4$reactivity is introduced into the core,the maximum temperature that the fuel can reach is 2059 K,which is 914 K lower than the fuel melting point.The system finally has the ability to achieve a new steady-state with a higher reactor power.When the GCR is shut down in an emergency,the residual heat of the reactor can be removed through the conduction of the core and radiation heat transfer.The results indicate that the designed GCR is inherently safe owing to its negative reactivity feedback and passive decay heat removal.This paper may provide valuable references for safety design and analysis of the gas-cooled SNRP coupled with CBC.
基金supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2013162-2017)the Defense Industrial Technology Development Program of China(No.D040301)。
文摘We propose a color ghost imaging approach where the object is illuminated by three-color non-orthogonal random patterns. The object’s reflection/transmission information is received by only one single-pixel detector, and both the sparsity constraint and non-local self-similarity of the object are utilized in the image reconstruction process. Numerical simulation results demonstrate that the imaging quality can be obviously enhanced by ghost imaging via sparsity constraint and nonlocal self-similarity(GISCNL), compared with the reconstruction methods where only the object’s sparsity is used. Factors affecting the quality of GISCNL, such as the measurement number and the detection signal-to-noise ratio, are also studied.